In recent years, a battery using as a negative electrode a carbon material such as graphite and using as a positive electrode a lithium-containing metal oxide such as LiCoO2, has been proposed. This battery is a so-called rocking chair battery such that after it is assembled, lithium ions are supplied from the lithium-containing metal oxide as the positive electrode to the negative electrode by charge, and lithium ions are returned from the negative electrode to the positive electrode by discharge. This battery is called a lithium ion secondary battery since no lithium metal is used for the negative electrode but only lithium ions are involved in the charge and discharge, and this battery is distinguished from a lithium battery using lithium metal. This battery is characterized by having a high voltage, a large capacity and high safety.
Further, as concern for environmental problems is increasing, storage system for clean energy by solar power generation or wind power generation, and power sources for electric automobiles and hybrid electric automobiles which replace gasoline-fueled automobiles, have been actively developed. Further, along with the tendency of on-vehicle apparatus and equipment such as power windows and IT devices to high quality and high functionality in recent years, a new power source has been required in view of the energy density and the output density.
As a storage device to be used for such an application which requires a high energy density and high power characteristics, in recent years, attention has been paid to a storage device called a hybrid capacitor comprising a combining storage principles of a lithium ion secondary battery and an electric double layer capacitor. As one example, an organic electrolyte capacitor has been proposed (for example, Patent Document 1) in which as a negative electrode, a carbonaceous material capable of absorbing-desorbing lithium ions and increasing drastically energy density by preliminary absorbing and supporting lithium ions (hereinafter sometimes referred to as doping) by a chemical or electrochemical method to lower the negative electrode potential, is used.
Such an organic electrolyte capacitor is expected to have high performance, but has drawbacks such that when the negative electrode is preliminarily doped with lithium ions, the doping requires a very long time, and it tends to be difficult to make lithium ions be uniformly supported by the entire negative electrode. Particularly, a large-size large capacity cell such as a cylindrical apparatus having electrodes wound or a rectangular battery having a plurality of electrodes laminated, has been considered to be hardly used practically.
To solve such problems, an organic electrolyte battery has been proposed (for example, Patent Document 2), wherein each of a positive electrode current collector and a negative electrode current collector has pores penetrating from the front surface to the back surface, a negative electrode active material is capable of reversibly supporting lithium ions, and lithium ions are supported by the negative electrode by electrochemical contact with a lithium metal disposed to face the negative electrode or the positive electrode.
In the organic electrolyte battery in which the electrode current collector has pores penetrating from the front surface to the back surface, lithium ions can move from the front surface to the back surface of the electrode without being blocked by the electrode current collector. Thus, even in a storage device having a cell structure with a number of electrodes laminated, it is possible to make lithium ions be electrochemically supported by not only a negative electrode disposed in the vicinity of lithium metal but also a negative electrode disposed distant from lithium metal, via the through-pores.
Patent Document 1: JP-A-8-107048
Patent Document 2: WO98/033227